I think they need to get rid of Brand asap so they can develop Speights and Young more, but they're in a good position at the moment.
Holliday, Turner, Iguodala, Speights, Dalembert, Young, Williams is indeed a really nice young group. Dalembert of course isn't ideal but he rebounds and blocks shots well. They need him because a Young / Speights front-court would be too short.
I don't think the Sixers will be very good for a while, but in a few years (and maybe another couple mid to high 1st round picks) and they could rise towards the top.
Looking like the best Eastern teams of the next decade could be the Sixers, Wizards, Bulls, Magic, Nets and whoever ends up with the best FA combo this summer (my guess is the Heat). Celtics could be among that group if Rondo continues to wow even after the Big 3 are done, and if Danny does a good job with the rebuilding process over the next few years.